<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      function balance() {
        let Bank = +prompt('请输入银行卡金额')
        let room = +prompt('请输入当月食宿消费金额')
        let life = +prompt('请输入当月生活消费金额')
        let card =Bank - room - life
        return card
      }
      alert(`银行卡剩余金额：${balance()}`)
    </script>
  </body>
</html>
